Garlic is one of the oldest horticultural crops. Worldwide production of garlic is nearly 10 million tonnes on nearly a million hectares. Because garlic seedlings grown from true seeds lack vigor and plants in these early generations can manifest unfavorable growth characteristics (such as deformed leaves, stunted roots, and limited bulb production), garlic production relies upon asexual propagation of the crop. The growth of a garlic plant typically begins from an individual clove that has been exposed to cool temperatures (15° C. or less) and depleted or “broken” dormancy (Rahim and Fordham, Scientia Hort. 37:25-38, 1988; Takagi, H. 1990. Garlic Allium sativum L. p. 109-146. In: J. L. Brewster and H. D. Rabinowitch (ads.), Onions and allied crops, v. III. biochemistry. food science, and minor crops. CRC Press. Boca Raton, Fla.). The root system and flat leaves usually develop before clove initiation (bulbing) ensues from inner (younger) leaf axillary buds. Plant maturation and senescence usually ensues after garlic bulb production. As the main stem of the bulb die, intact and living basal plates remain on each clove to carry on future growth.
The major distinction among garlic clones is the tendency to produce a flower stalk, or not. Those producing a flower stalk are referred to as “bolting,” “stalking,” or “hard neck” types, whereas those without a flower stalk are “non-bolting,” “non-stalking,” or “soft neck.” Sometimes a third category, “incomplete or partial bolting,” is used for clones in which the inflorescence begins to develop but stem elongation is incomplete and mature flowers do not develop.
Development of the floral apical meristem in bolting garlic requires exposure to low temperatures (such as less than 5° C.) before onset of the primary growth period. Complete bolting in garlic involves floral induction, scape elongation, inflorescence development, and floral maturation. During scape elongation, the meristematic region at its tip begins to differentiate floral initials and subdivides into identifiable flowers interspersed with bulbils. Because development of the garlic seed stalk precludes further vegetative growth, garlic farmers remove and discard the scapes to promote growth of the garlic cloves.
Current methods of garlic bulb production include planting a clove of or from a mature garlic bulb in the fall (in the Northern Hemisphere). In the spring or early summer, fresh garlic shoots appear from the cloves.
Garlic and extracts thereof have been indicated to have positive effects on circulation and pulmonary function, as well as potential anti-cancer affects (for example see WO 99/21008). Most of the active ingredients in crushed garlic are sulfur-containing compounds. Allicin (thio-2-propene-1-sulfinic acid S-allyl ester) is the primary component that is understood to produce many of the medicinal benefits attributed to garlic. The intact garlic clove does not contain allicin, but rather contains its precursor alliin (S-allyl-L-cysteine sulfoxide). Allicin is formed by crushing garlic, which allows the enzymatic conversion by alliinase (C-S-lyase, also known as alliin lyase [E.C. 4.4.1.4]) of alliin to allicin, as well as pyruvate, and ammonia. Alliin and alliinase are found in different compartments of the garlic cloves. When garlic is cut or crushed, the membranes of these compartments are broken so that the enzyme can react with alliin.
Although many health benefits of garlic have been observed, such benefits are reduced by cooking garlic, since the therapeutic compounds in garlic are adversely affected by heat. Unfortunately, most individuals do not prefer to eat significant quantities of raw garlic cloves. Furthermore, processes which dry garlic to make it into a powder or pill also change the composition and concentration of the sulfur-containing compounds. Therefore, the ability to provide these therapeutic compounds in a fresh vegetable which can easily be consumed raw (uncooked) is desirable.